PubMed Health⌕ Search

Biomedical subjects

V J Robertson

Publications and source records attributed to V J Robertson.

At least 19 recordsLinked to original sources
PubMed2000

Setting safe and effective suction pressure: the effect of using a manometer in the suction circuit.

OBJECTIVES: To establish the levels of pressure used to perform tracheal suction (TS) and if they are affected by having a manometer visible in the suction circuit. DESIGN: A bench test evaluation of simulated tracheal suction. SETTING: Physiotherapy department of a major teaching hospital in Melbourne, Australia. PARTICIPANTS: Sixty-four nurses and physiotherapists who regularly apply TS to patients in the intensive care units of this hospital. INTERVENTIONS: All subjects used both circuit A (without a visible manometer) and B (with a visible manometer) in a predetermined random order. For both, subjects adjusted the suction control tap to where they said a safe and effective pressure (set pressure) was delivered and then occluded the suction catheter as though suctioning (applied pressure). Subjects then completed a questionnaire on their current TS practise. MEASUREMENTS AND RESULTS: All set pressures (mean = 228.57 mmHg) and all applied pressures (mean = 359. 52 mmHg) were significantly higher (P <.001) when compared to the expected pressures (mean = 135 mmHg). Pressures set without a visible manometer (circuit A) were significantly higher (P <.05) than those using a visible manometer (circuit B) but the applied pressures were not significantly different (P =.166). Neither the investigator (P =.618) or the test order (P =.167) had a significant effect on the outcome. Questionnaire results showed 31 % of subjects considered 100-170 mmHg a safe and effective suction pressure whilst none reported using an objective means of measuring pressure. CONCLUSION: All pressures in both circuits were significantly higher than those recommended as safe in the literature. In addition, pressures were unaffected by the inclusion of a visible manometer in the suction circuit.

Adult↗
PubMed2000

Work-related musculoskeletal disorders in physical therapists: prevalence, severity, risks, and responses.

BACKGROUND AND PURPOSE: Physical therapists are at risk for work-related musculoskeletal disorders (WMSDs). Little is known of how therapists respond or of what actions they take to prevent injury. The purpose of this study was to investigate the prevalence and severity of WMSDs in physical therapists, contributing risk factors, and their responses to injury. SUBJECTS: As part of a larger study, a systematic sample of 1 in 4 therapists on a state register (n=824) was surveyed. METHODS: An 8-page questionnaire was mailed to each subject. Questions investigated musculoskeletal symptoms, specialty areas, tasks and job-related risk factors, injury prevention strategies, and responses to injury. RESULTS: Lifetime prevalence of WMSDs was 91%, and 1 in 6 physical therapists moved within or left the profession as a result of WMSDs. Younger therapists reported a higher prevalence of WMSDs in most body areas. Use of mobilization and manipulation techniques was related to increased prevalence of thumb symptoms. Risk factors pertaining to workload were related to a higher prevalence of neck and upper-limb symptoms, and postural risk factors were related to a higher prevalence of spinal symptoms. CONCLUSION AND DISCUSSION: Strategies used to reduce work-related injury in industry may also apply to physical therapists. Increased risk of thumb symptoms associated with mobilization techniques suggests that further research is needed to establish recommendations for practice. The issues for therapists who move within or leave the profession are unknown, and further research is needed to better understand their needs and experiences.

Adult↗
PubMed1998

Sensory, motor, and pain thresholds for stimulation with medium frequency alternating current.

OBJECTIVES: To investigate the effect of frequency of alternating current on the sensory, motor, and pain thresholds in normal subjects, and to establish the optimal frequency for motor stimulation with minimal subject discomfort. DESIGN: A repeated measures design using two groups of 11 subjects. SETTING: A laboratory setting was used. PARTICIPANTS: Participants were volunteers who met the inclusion criteria. INTERVENTIONS: Alternating current with 20 different carrier frequencies between 1 and 35 kHz, all modulated at 50 Hz, was applied to each subject on two separate occasions. For half the subjects, the frequency was increased or decreased sequentially (reversed on second occasion), and for the other half, it was applied in a different random order on each occasion. MAIN OUTCOME MEASURES: The voltage at the sensory threshold was recorded for each applied frequency. This was subsequently repeated for motor and pain thresholds. RESULTS: Sensory, motor, and pain thresholds decreased with increasing frequency between 1 kHz and approximately 10 kHz. Above 10 kHz, the thresholds increased. The ratio pain threshold/sensory threshold increased systematically with increasing frequency over the range examined. By contrast, the ratio pain threshold/motor threshold showed a distinct maximum at a frequency of 10 kHz. Marked accommodation to motor and pain fiber stimulation was observed. CONCLUSIONS: For comfortable sensory stimulation, a high frequency of alternating current is preferable. Discrimination between pain and motor stimulation is maximal at a frequency of approximately 10 kHz. This suggests that the optimal frequency for comfortable motor stimulation, one that is least likely to elicit pain fiber stimulation, is close to 10 kHz.

Adult↗
PubMed1998

Variation in torque production with frequency using medium frequency alternating current.

OBJECTIVES: To investigate the effect of frequency of alternating current on electrically induced torque in healthy subjects, and to establish an optimum frequency for motor stimulation. DESIGN: A repeated-measures design using 12 subjects (part 1) and 3 subjects (part 2). SETTING: A laboratory setting was used. PARTICIPANTS: Participants were volunteers who met the inclusion criteria. INTERVENTIONS: Alternating current with carrier frequencies between 1 and 15kHz, modulated at 50Hz, was applied to each subject on two separate occasions. The frequencies were applied in a different random order on each occasion and different random orders were used between subjects. For part 1 of this study, six frequencies were used: 1, 2, 4, 7, 10, and 15kHz. For part 2, three frequencies were used: 1, 4, and 10kHz. MAIN OUTCOME MEASURES: Part 1: The maximum electrically induced torque, defined as the torque induced at the pain threshold, was recorded for each applied frequency. Part 2: The variation of torque with increasing stimulus intensity was recorded for each applied frequency. RESULTS: Highest electrically induced torque was produced at the lowest frequency examined (1kHz). Torque decreased systematically with increasing frequency over the frequency range examined. The rate of increase in torque with applied stimulus intensity was also found to decrease systematically with increasing frequency in a way that depended strongly on the skinfold thickness of the subject. CONCLUSIONS: Electrical stimulators using an alternating current waveform typically use a carrier frequency in the range of 2kHz to 4kHz for motor stimulation. This study shows that carrier frequencies in this range, modulated at 50Hz, are a compromise between comfort and maximum torque production. For maximum comfort with a low torque, a frequency close to 10kHz is indicated. For maximum torque, a lower frequency of alternating current (1kHz or less) is preferable.

Adult↗
PubMed1998

Cryptococcal meningitis in human immunodeficiency virus-infected patients in Harare, Zimbabwe.

A prospective observational study was conducted over a 10-month period to determine the clinical and laboratory manifestations of cryptococcal meningitis in Zimbabwe, a country where antifungal agents are not widely available. Eighty-nine patients with cryptococcal meningitis (median age, 34 years; range, 11-63 years; 56 males) were identified from 406 patients for whom a clinical diagnosis of meningitis had been made. All patients tested were positive for antibody to human immunodeficiency virus. Cryptococcal meningitis was the first AIDS-defining illness in 88% of patients. Typical presentations were headache, mental impairment, and meningism (median duration, 14 days; range, 1-180 days). The median CD4+ cell count was 70/microL (range, 0-651/microL). The cumulative median survival from the time of diagnosis was 14 days (range, 0-233 days); 22% of patients survived for >30 days. Independent indicators of a good prognosis were not identified. This study provides a unique basis for the development of novel management strategies for patients with cryptococcal meningitis who reside in resource-poor countries.

AIDS-Related Opportunistic Infections↗
PubMed1998

Thoracic spiral CT: influence of subsecond gantry rotation on image quality.

PURPOSE: To determine if the lower milliampere second setting and shorter acquisition time of subsecond spiral computed tomography (CT) affects the image quality of thoracic CT scans. MATERIALS AND METHODS: In 92 consecutive outpatients referred for thoracic CT, spiral CT (120 kV, 292 mA) was performed with 1-second (n = 45) or 0.75-second (n = 47) scanning time. An equal percentage of patients (70%) in each group received intravenous contrast medium. At six mediastinal and six lung zones, degradation due to motion and noise, respectively, were graded independently on a four-point scale by three blinded radiologists. Statistically significant differences were determine with a two-tailed test. RESULTS: Mediastinal image quality was significantly better on 0.75-second scans than on 1-seconds scans (P < .001). Regions with the greatest improvement in image quality were around the aortic root, cardiac ventricles, and aortic arch. Lung image quality was also better on 0.75-second scans than on 1-second scans (P = .04). On 0.75- and 1-second scans, respectively, motion-related artifacts were found to degrade image quality 6.2 and 8.7 times more than noise-related artifacts in the mediastinum and 2.6 and 3.9 times more in the lungs. CONCLUSION: Subsecond spiral CT is associated with improved clarity and diminished motion artifacts on mediastinal and pulmonary images when compared with 1-second spiral CT.

Adolescent↗
PubMed1996

Limited interchangeability of methods of applying 1MHz ultrasound.

OBJECTIVE: To investigate the interchangeability of two different methods used to apply 1 MHz ultrasound for deep tissue heating, namely, the direct contact and the subaqueous methods. DESIGN: An intervention study with a crossover design. SETTING: The setting was a laboratory. PARTICIPANTS: Four specimens, cross-sections of nonliving pig tissue, were used. INTERVENTIONS: Specimens were each exposed to 1 MHz ultrasound under five different conditions: in contact with gel, and subaqueous at 0, 1, 2, and 4 cm from the applicator to the skin. MAIN OUTCOME MEASURES: Tissue temperatures were measured at six thermocouple sites at different depths from the skin surface. RESULTS: Subaqueous ultrasound applied at a distance of 0 cm from the skin produced significantly less tissue heating than direct contact (with gel) ultrasound at the same intensity. Increasing the distance from the applicator to the skin from 0 to 1, 2 and 4 cm resulted in significantly lower mean maximum temperature increases of 69%, 56%, and 44%, respectively, of the 0 cm values. CONCLUSIONS: The methods used clinically to apply ultrasound have only limited interchangeability. Large corrections to the power output are required to compensate when using subaqueous rather than direct (in air) ultrasound, and for applicator to skin distances of beyond 0 cm in subaqueous ultrasound.

Animals↗
PubMed1996

Dosage factors for the subaqueous application of 1MHz ultrasound.

OBJECTIVE: To determine and validate correction factors necessary to ensure consistent dosage of 1MHz ultrasound when applied in water at different applicator-to-skin distances and different levels of intensity. DESIGN: An intervention study with a crossover design. SETTING: A laboratory. PARTICIPANTS: Cross-sections of nonliving pig tissue. INTERVENTIONS: Specimens were each exposed to 1MHz ultrasound under four subaqueous conditions: in contact with the skin and at 1, 2, and 4 centimeters from the applicator to the skin. These conditions were repeated for each of three intensity levels: 0.5W/cm2, 1.0 W/cm2, and 2.0 W/cm2. MAIN OUTCOME MEASURES: Tissue temperatures were measured at six thermocouple locations at different depths from the skin surface. RESULTS: Increasing the distance from the applicator to the skin from 0 to 1, 2, and 4 centimeters resulted in progressive and significantly lower mean maximum temperature increases. The same relation of distance to temperature increase was identified at all intensity levels and was used to calculate dosage factors for distance in water. By multiplying the required intensity by the calculated dosage factors, the temperature increases in tissue were found to equal those produced at 0 centimeters distance. CONCLUSIONS: Large corrections to the intensity output are required to compensate when using ultrasound in water at different applicator-to-skin distances. These dosage (correction) factors are reliable for the range of intensity levels tested under the conditions examined.

Analysis of Variance↗
PubMed1996

Comparison of heating of nonliving soft tissue produced by 45 kHz and 1 MHz frequency ultrasound machines.

Ultrasound of 1 MHz frequency is used routinely for patient treatment because it can penetrate to and heat deeply located tissue. Benefits are claimed for newly introduced 45 kHz ultrasound machines, yet little evidence is available to confirm these benefits. This paper compares claims supporting the therapeutic use of 45 kHz ultrasound with those supporting the traditional MHz frequencies. The results of an empirical study comparing the heating effects are also presented. Thermocouples placed at different tissue depths in nonliving pig tissue measured temperature variations over a 40-minute period. Direct heating produced by the 45 kHz ultrasound machine was very superficial. By contrast, the 1 MHz ultrasound machine produced direct heating at all tissue depths. The results confirmed that although 45 kHz ultrasound machines may be useful for heating superficial tissues, they have limited or no use in heating deeper tissues. For treatment of deeply located tissue, 1 MHz ultrasound should continue to be used.

Hot Temperature↗
PubMed1995

Pneumocystis carinii pneumonia in Zimbabwe.

Pneumocystis carinii pneumonia (PCP) is said to be rare in Africa, with reported rates of 0-22% in human-immunodeficiency-virus (HIV) infected individuals with respiratory symptoms. Over one year in a central hospital in southern Africa, 64 HIV-infected patients with acute diffuse pneumonia unresponsive to penicillin and sputum smear-negative for acid-fast bacilli underwent fibreoptic bronchoscopy. Bronchoalveolar lavage fluid was assessed for bacteria, fungi, Pneumocystis carinii, and mycobacteria. 21 patients (33%) had PCP and 24 (39%) had tuberculosis; 6 of these had both infections. 5 patients had Kaposi's sarcoma (KS) associated with PCP, tuberculosis, or another infection, in 1 patient KS was the only finding, and in 21 no pathogen was identified. A logistic regression model was used to assess clinical, radiographic, and arterial blood gas predictors of PCP and tuberculosis. Fine reticulonodular shadowing on the chest radiograph (nodular component < 1 mm) was the strongest independent predictor of PCP (odds ratio 8.5 [95% CI 6.1-10.9]). A respiratory rate of more than 40/min was the best clinical predictor of PCP (odds ratio 11.2 [95% CI 8.8-13.6]). Median CD4+ T cell count for all cases of PCP was 134/microL (range 5-355) and for tuberculosis without PCP 206/microL (range 61-787). In resource-limited countries, a regionally appropriate management algorithm is required.

AIDS-Related Opportunistic Infections↗
PubMed1995

Subaqueous ultrasound: 45kHz and 1MHz machines compared.

This study compared the tissue heating produced by 45kHz and 1MHz ultrasound machines used subaqueously in metal and in plastic basins. An intervention study with cross-over design was used. The setting was a laboratory. Two cross-sections of nonliving pig tissue were used with thermocouples positioned, in the tissues, at different distances along the ultrasound beam axis. Specimens were each exposed subaqueously to ultrasound produced by a 45kHz machine and a 1MHz machine. Both metal and plastic treatment basins were used (2 machines x 2 basin types). Thermocouples measured temperature variations for 30 minutes with each machine on and 10 minutes with it off. Temperature increases at different tissue depths varied with both the ultrasound machine and the type of basin used. The 45kHz frequency ultrasound machine produced a maximum temperature increase of 0.4 degrees C and an initial rate of heating of 0.05 degrees C per minute. The 1MHz machine consistently produced greater temperature increases. These were further increased by 2.65 degrees C (average) if a metal rather than plastic basin was used. The 45kHz machine, operated at maximum output, produced little heating of the irradiated tissue. By contrast, the 1MHz ultrasound unit produced appreciable heating to almost the full depth of the tissue irradiated. Use of a metal basin, rather than plastic, resulted in a markedly higher maximum temperature increase and a significantly greater initial rate of heating.

Animals↗
PubMed1995

Research and the cumulation of knowledge in Physical Therapy.

BACKGROUND AND PURPOSE: Published research contributes to the knowledge base that distinguishes one discipline from another. More research is now published in the physical therapy journals, but concerns with the profession's knowledge base continue. SUBJECTS: The study examined citations from 78 clinical articles published and indexed on three thematic areas in Physical Therapy between 1951 and 1990. METHODS: Unique items and multiple-cited items were identified and counted and their sources ascertained. Linkages among multiple-cited items in each thematic area were identified and described. RESULTS: Most cited items were unique and not from the physical therapy literature. Few linkages were identified among the clinical articles. CONCLUSION AND DISCUSSION: The lack of evidence of cumulation or of coherence among the articles examined and the extent of reliance on non-physical therapy sources suggest that concerns with the knowledge base of the profession are well founded.

Forecasting↗
PubMed1995

A quantitative analysis of research in Physical Therapy.

BACKGROUND AND PURPOSE: Some physical therapists argue that research will justify and improve practice in the discipline. Whether these outcomes can be realized is partly a function of the nature of the research, the research methods used, and the extent to which clinical treatments are investigated. SUBJECTS AND METHODS: This study analyzed aspects of a sample of 272 articles published in Physical Therapy during 1954 through 1993. Each article was read and categorized according to the method used and to whether it investigated clinical treatments. RESULTS: An increasing percentage of the articles sampled described studies that used group designs, and most of the studies did not investigate clinical treatments. CONCLUSION AND DISCUSSION: These findings are paradoxical given existing criticisms of group designs and expectations in physical therapy of research. More discussions and evaluations of current research practices in physical therapy are needed.

Longitudinal Studies↗
PubMed1993

HIV and other sexually transmitted diseases at a rural hospital in Zimbabwe.

OBJECTIVE: To define the epidemiological characteristics of STD patients attending an outpatient clinic in rural Zimbabwe, to examine the aetiologic agents causing infection and to determine their relationship with HIV infection. SUBJECTS: 319 men and 146 women, making a sample of about 7% all patients attending an STD clinic during the 3 month study period. Microbiological data were collected from 104 men and 72 women selected randomly from these. Pregnant women were excluded and patients who had received antibiotics within the previous 14 days were excluded from the microbiology sub-sample. SETTING: An outpatient STD clinic at a District Hospital on a major truck route about 300 km north of the capital, Harare. METHODS: All new patients attending the clinic during a 3 month period were enrolled for clinical and epidemiological investigations using a standard procedure. Specimens for microbiological investigation were taken from every second patient seen on the first three days of each week. RESULTS: The typical patient was male (m:f ratio 2.2) aged 20-29 years (68% patients), not married (56% men) and in paid employment (66% men vs. 27% for the district). In men the most common presenting feature was genital ulceration, while in women, discharges were more common. Genital warts were noted frequently in both sexes. In the sub-sample examined microbiologically, H ducreyi was isolated from 46% ulcers clinically diagnosed as chancroid, and motile spirochaetes were detected in 25% painless ulcers. Neither of these were detected in ulcers in women, but HSV antigen was found as frequently in ulcers from men (19%) as from women (17%). In patients with genital discharges, gonococcal infection occurred in 64% men and 17% women, while T vaginalis was isolated from 39% women and only 8% men. Over 60% gonococcal isolates were PPNG, and 18% showed in vitro resistance to tetracycline. Yeasts, mainly C albicans were isolated from 42% women with a discharge and 25% women with ulcers. In men the presence of yeasts was associated with superficial ulceration and itchiness of the glans. Positive HIV-1 serology was found in 64% patients. There was no statistical association with current genital ulcers, though there was an association with previous STD episodes and particularly with serological evidence of syphilis. Apart from yeasts, there was no association between positive HIV-1 serology and the presence of pathogens in the genital tract. CONCLUSIONS: The high prevalence of HIV-1 antibodies in STD patients in Karoi suggests integration of STD and AIDS control programmes to be a necessity. Since paid employment was a common feature of both STD clinic attendance and HIV-1 seropositivity, these programmes may be effectively directed through the work place.

Adolescent↗
PubMed1993

Salmonella and shigella bacteraemia in Zimbabwe.

In patients with HIV infection, non-typhoidal salmonellae are a recognised cause of bacteraemia. This association was initially demonstrated in the United States, but has more recently been found in Kenyan patients. This prompted us to review the cases of patients with enterobacteriaceae bacteraemia admitted to Parirenyatwa Hospital, Harare. Non-typhoidal salmonella bacteraemia as compared with typhoid fever was significantly more common in HIV infected patients than in non-HIV infected patients (p < 0.01). It was also a cause of bacteraemia in patients with other immuno-suppressive conditions and in some patients without identifiable risk factors.

AIDS-Related Opportunistic Infections↗